In engine control units of internal combustion engines (gasoline and diesel), the torque-determining injections are controlled by a microcontroller as a processing unit. This activates a downstream activation circuit via its output port, in particular in the form of an application-specific integrated circuit (ASIC) including output stages (so-called injection output stage component), which in turn activates the injection valves (injectors), i.e., typically connects them in a defined manner to a power or voltage source.
Injection systems are among the safety-relevant systems for which a safety concept is advantageous. The safety concept may be represented, for example, by a multilevel concept. In safety-critical function units in vehicles, for example, in the electronic engine filling control system (EGAS), for example, a so-called three-level concept may be used for safety monitoring in the operating control unit. Mutual monitoring within the control unit between the function computer (processing unit, CPU) and a separate monitoring module (UM or watchdog) is essential. Function computer and monitoring module communicate via a question/answer communication and in the event of an error may shut down power output stages in the control unit, which are provided for operating the function unit, and thus ensure the safety of the vehicle. In present electronic engine filling control systems, the entire function and monitoring software is in a control unit, as described in German Patent No. DE 44 38 714 A1.